System of space discharge devices



July 2, 1929. E. J. STERBA 5 v SYSTEM OF SPACE DISCHARGE DEVICES Filed Feb. 25, 1924 Patented July 2, 1929.

UNETED STATES PATENT OFFICE.

ERIHZZST J. STERBA, OF IZEIV YORK. N. Y., ASSIGNOR TO WESTERN ELECTRIC COMIPANY, INCORPORATED, 015 NEW YORK, N. Y., .A CORPORATION OF NEW YORK.

SYSTEM OF SPACE DISCHARGE DEVICES.

Application filed February 25, 1924. Serial No. 694,864.

This invention relates to systems of space dircharge devices and more particularly to an arraogement whereby a plurality of three electrode devices of this type may be connected in parallel.

In systems includii'ig parallel connected three electrode discharge devices heretofore proposed, the, devices have been arranged in a single row. or at the angles of an irregular geometrical figure. The conductors through which energy is supplied to and from the electrodes of the discharge devices to a load circuit have been connected at one end of the row or at some point on the geometrical figure which is not; symmetrically positioned relatively to the leads connectiug the electrodes of the several devices to the energy supply conductors. Again, \vhere anti-singing choke coils have been used in the output circuits of the devices, they have in general been connected into each circuit at some point remote from the anode of the device.

\Vhen three electrode space discharge devices are used to amplify alternating current, it is well known that, because of distorting action of the devices, current components of frequencies harmmiically related to the frequency of the amplified current will be produced in the circuits associated with the devices.

Again. when devices of this type are used as amplifiers, there is a tendency to produce sustained oscillations, or singing, due to feeding back some of the amplified energy to the input side of the amplifier circuit. The amplified energy may he ted back by any coupling relation between the input and output circuits of the amplifier. A common form oli coupling is the internal capacities between the electrodes of the dis charge devices. If the tendency to develop sustained oscillations is very marked, it impossible to realize a high degree of amplification, since the amplifier must be operatcd to give a smaller amplification than that at which sustained oscillations occur.

In amplifier systems heretofore proposed, as described above. the "frequency of the parasitic oscillations produced are harmonically related to the frequency of the energy to be transmitted through the systel'n. They are in general caused by the distorting action of the space discharge devices, the

unequal lengths of the conductors connecting the source of input energy to their control electrodes, and the fact that the antisinging choke coils are included in the out put circuits at points remote from their anodes.

The reason for this resides in the fact that the input conductors possess ditlerent values of inductanc and capacity which co operate with the inductances and capacities of the leads between the anode and the choke coils to build up the amplitudes of the barmonically related impulses produced by the devices until they are of sutlicient value to produce sustained oscillations at these frequencies. The tendency to produce parasitic oscillations directly proportional to the lengths of the grid and anodt choke coil leads.

This invention provides an amplifying system, including parallel connected three electrode space discharge devices. in which the production of undesired oscillations is limited to a single frequency. and antisinging choke coils are included in the output circuits of the devices to more etliciently suppress these oscillations than in the sys- -tems heretofore proposed.

In accordance with this invention a plu rality of parallel-connected three electrode space discharge devices are mounted on a supporting panel in two groups, one group projecting upwardly and the other downwardly from the panel, with the corre sponding devices of each group in axial alignment. The control electrodes of the groups of devices are connected in pairs by short leads which are connected to a centrally positioned common lumbar. The midpoint of the bus-bar is connected by a conductor to the source supplying energy to the control electrodes. and anti-singing choke coils are mounted on the anode terminal contacts of the devices.

The primary object ol this invention is to increase the elliciency of parallel-connected space discharge devices.

Another object is to reduce the tendency ol parallel connected space discl'iarge de vices to produce sustained oscillations of undesired frequencies.

A further object of the invention is to suppress parasitic impulses at the, output terminals of the discharge devices.

ltlt) A feature of this invention is to provide a system for connecting a plurality of space discharge devices in parallel so that each device supplies the same amount of energy to a load circuit.

Another feature is the provision t a. symmetrical connection for the control electrodcs ot' a plurality of parallel connected space discharge devices.

A further feature is to provide conductive paths ot' substantially equal lengths t'or connecting the input supply source to the control electrodes of parallel-connected space discharge devices.

A still t'urther feature is the provision of means whereby the necessary auxiliary apparatus may be included in the output cir cuits of the discharge devices without cansing the production of parasitic oscillation.

For a. complete innlerstamling ot the invention and the operation of its various parts, reference should he made to the following description read in conjunction with the attached drawing in which, Figs. 1 and 2 show respectively front. and side views ot the suppm'ting structure for the discharge devices and Fig. 3 illustrates a. radio transmitter to which the invention is applied.

In the various figures of the drawings the same reference characters are used to indicate the same parts.

Referring to Figs. 1 and 2 there is shown a frame comprising a vertical panel 1, a base 2. standards 3 and a horizontal panel or mounting plate 4 secured at its inner edge to the panel l and at its outer edge to the base 2 by the standards 3.

Space discharge devices 5 are mounted in sockets G secured to the upper and lower faces of the panel 4 to constitute two sets 7 and 8.

Each of the sets 7 and 8 comprises six devices arranged in two groups. ()no group of each set consists of three devices projecting vertically above the panel t and a second group of three devices projecting downwardly from the panel 1. The corresponding devices of the two groups are arranged co-axially to t'orm a pair.

The two sets of devices are therefore syn-inletrically positioned relatively to the panel 4 and the space occupied by each set is determined by the number of devices included in it. by the dimensions of the bases 0 and by the heights of the devices 5.

The sockets G are each provided on one face with a pair of filament contacts 9 and a contact 10 for the. impedance control electrode or grid. On the opposite face of the base is an anode contact 11.

The corresponding contactst) of the a ially aligned devices are connected together by leads .12 which are in turn comiccted to a common conductor 13 leading to one ter minal of a source for supplying heating current to the filaments. he other terminal. of the heating current source. is connected to the other tilamcnt contacts t) by separate conductors l t.

The contacts it) for the impedance control electrodes are connected in pairs to a common comlucior or busbar l5 lying in a hm'iaontal plane ccntratly ot' the contacts lit. The midpoint ot" the busbar 1.3 is connected by a conductor It to a binding post lT mounted on the panel 1. The source of input energy is connected to the binding post l7 and to the filament conductor 13.

Mounted on and electrically connected to each ot' the anode contacts ll, as shown in Fig. 1, is a choke coil to.

The choltc coils lb are de igned to provide a. low impedance path ol -alternating current. of the frequency to be amplifi d by the devices 5, but to impose an impedance adapted to substantially prevent. the tlow of alternating current components of frequencies harmonically related to that. of the amplified current.

he control rte-trodes ot the devices are symmetrically connected by the busbar t5 and conductor 10 to the source supplying input energv. The leads extending from the busbar 15' to the contacts 10 are very short and the lengths of the crmductors connect ing the control contacts ot the dill'crent devices to the input. source are substantially equal. circuit for each ot the devices will be equal and hence the same voltage will be impressed upon their control electrodes. with the result that. the impedance of the space ,path within each ampliticr is the same and amplified currents ot the equal am ditudcs will be supplied to the load circuit by each of the devices.

By mounting the choke coils directly upon the anode contacts ll any impulses ot undesired frequencies will bc suppressed at the output terminal ot' the devices. These coils should have such impedance that they serve to determine the impedance of the out put leads lot the energy to he ampliticd. with the result that any desired length ot' lead, including the ncccs.-ary auxiliary ap paratus, may be used for supplying energy of desired frequency to the load circuit without causing parasitic osciilatiims to be produced in the circuits of the system.

As shown in Fig. 1. the output. circuit of each of the six parallel coimccted devices constituting a set may be. traced from its contact. ll through the choke coil 19. jack l9. fuse to a common conductor 21 which connected to a binding post 22 mounted on the panel 1. As is usual the jacks 19 are employed to permit a meter to be included in the output circuit, whereby the current supplied by ach device to the cone mon conductor 21 may be measured. The

Thus the llllpGtltllltft ot' the input ltltl t'uses Qt) are used to protect the discharge devices against high potentials which may damage or even destroy them.

The syst m described above has been used in a radio telephone system similar to that shown in l ig. It in which a source 21- supplies low power waves ot carrier 'l'requemy through an asnplitier to a set of six parallel coi'inected discharge devices 53 t'or raising the carrier waves to high power. This set of devices may correspond to that shown at T in hig. l. The two parallel connected high power devices in this tignre are intended to represent a set of six. The output circuit ot' the amplifier E3?) is connected through a. coupling transl'ormer 2V to tho binding post; t7 and thence through the con ductor 1t) and the common input bus bar 15 to the grids. across the space within the de-- vices to their cathode and bach to the trait, torniel' 26.

The output circuits ol' the devices 5 in elude the choke coils 1s and are connected to the common output conductor 2t. The space current circuit may be traced t'rom the positive terminal of the source 2T, through high impedance chohe coil in. radio trequcney choke, coil 3t) antenna coupling coil :1]. conductor 2t and anti singing choke coils is, to the anodes. across the space within the devices to their lilaments and back to the negative terminal ot the. source 27. A condenser 32 provides a low impedance path t'or amplitied alternating current; in shunt. to the smnrce 27.

Low power speeeh currents are suppiied by thomicrophone(circuitZ111 through an amplitior 34 to the parallel connected set of amplifiers 8, herein represented by two devices.

The output circuit; of the amplifier St is coupled by a transt'ormer :35 to the input ot circuit ot' the parallel connected discharge devices comprising the set 8. One terminal oi tho secondary of the transformer :35 is connected. to the cathode of the discharge devices. The other terminal is connected to the binding post l7 which is in turn eonixeeted through the conductor 16 and eonnnon bushar 1.7 to the control. electrodes of the devices.

Space current. is supplied to the devices of set. S from the positive terminal oi the source *7, through the impedance choke coil as, common conductor 21, anti-singing eholt'o coils is to the anodes, aeross the space within tho devices to the cathodes and back to the negative terminal of the source ET.

The negative terminal oi' the source 527 is grounded at 37.

The high power speech currents 'tlow through the condense 38 to modulate the space current supplied to the high power devices comprising the set. 7. whereby high frequency waves having their amplitudes modulated in accordanee with speech are supplied through the coil 31. inductively as soeiated with the coil 39, included in the antenna circuit, for transmission to a distant station.

Although a set: consisting of six devices has been described above it will l apparent that by conneeting the control e ectrodes of the discharge devices to a common busbar having its midpoint connected to the source sup plying input energy thereto and mounting an anti singing choke coil on each anode coir tact, the principles ot this invention may he applied to a set comprising an odd or even number of devices.

From the preceding descriptioi'i it will be seen that this invention provides a system. including a plurality olparallel connected ;--:pace. discharge devices, in which singing can occur at but. one, t'rr-(pieney. the impedin-es ot the discharge path of the ditl'erent devices are equal and the maximum etl'eet ot' the anti-singilig choke coils in suppressing undesired oscillation is obtained.

'hile a certain specilic arrangement ol' the apparatus and its application to a particular use have been described tor the pin po-e ot' cleart and completely disclosing the nature oi the invention, it is to be understood that this invention is not limited to the speritio features or use disclosed but only by the scope of the attached claims.

What is claimed is:

1. Means tor supporting space discharge devices eomprising a horizontal panel and sockets tor said devices secured to the o posite t'aees ot said panel said oppositely disposed sockets being arranged in axial alignment.

2. Means tor supporting a plurality of space discharge devi es each having a plurality of electrodes, comprising a panel,

sockets tor said devices secnred to the opposite faces of said panel, said sockets being each provided with contacts corresponding to said electrodes. a conductor lying in a plane centrally ol said oppositely disposed sockets, means for connecting the contacts of eorresponding electrodes of said devices to said conductor and means for connecting the midpoint of said eomlurtor to a. binding post.

3. Means for supporting a plurality of spare discharge devices each having a plurality ot electrodes. comprising a horizontal panel. soelcets tor said devices secured to the opposite t'aces of said panel. said sockets being arranged in axial alignment and each. being' provided with contacts corresponding to said electrodes. a. conductor symmelrieally located with respect; to said sockets, and means For connecting corresponding contacts (it said sockets to said conductor.

4. .\n eleetrieal system comprising a plurality ot' three electrode space discharge dellt) viccs, external circuits for said devices, means for connecting one of said external circuits symmetrically to the corresponding electrodes of said devices, and parasitic oscillation suppressin; means included in the other external circuit closely adjacent the connection of other corresponding electrodes of said devices.

5. An electrical system comprising a plurality of space discharge devices, each having a cathode, an anode and an impedance control electrode: said devices having cathode-control electrode circuits which are of equal impedances a contact for each of said anodes and cathode-anode circuits, and means tor suppressing: undesired oscillations directly connected to each of said anode contacts.

ti. An electrical system comprising a plurality ot' space discharge devices, each having a cathode, an anode and an impedance control electrode, said devices having cathode-control electrode circuits which are of equal impedances, a contact for each of said anodes, and anti-singing choke coils mounted upon and connected to each of said anode contacts.

'4'. An electrical system comprising a plurality ot three electrode space discharge devices, said devices being coupled to external circuits by input and output circuits adapted to permit singing at one undesired fre quency only, and means. included in said output circuit closely adjacent the pointot' origin ot' impulses ot' undesired 't'rcquency, tor reducing said impulses to negligible amplitudes.

In Witness whereof I hereunto subscribe my name this 23rd day of February A. D., 1922-1.

ERNEST J. STERBA. 

